Polycarbonate polymers are thermoplastic resins that are useful in a number of plastic material applications including, for example, injection molding, extrusion, rotation molding, blow molding, thermoforming, and the like. Polycarbonate thermoplastic resins exhibit a number of advantageous material properties and mechanical properties including, for example, high impact strength, excellent dimensional stability, glass-like transparency, excellent thermal resistance, and low-temperature toughness. These properties, among others, make polycarbonate thermoplastic resins attractive as engineering materials for a wide variety of applications including, for example, automotive and transportation, building and construction, electrical and electronics, telecommunication, packaging, medical, optical/opthalmic, and optical media. In various applications, flame-retardancy is an important property, for example, in electrical and electronics applications, such as appliance and equipment housings and parts.
Weider, et al., in U.S. Pat. No. 5,693,697 describe the inclusion of 0.5% of diphenyl dimethoxysilane as a flame retardant additive in combination with 0.1% of potassium perfluorobutane sulfonate to provide a composition exhibiting a flame retardance UL94-V0 at 2.6 mm. However, the boiling point of the additive is 304° C. at 760 mm Hg, which is too low for typical extrusion compounding and injection molding of polycarbonate (at 300-370° C.).
U.S. Pat. No. 6,727,302, issued to Goossens, et al., discloses poly(methylphenyl-siloxane) as an efficient flame retardant additive in combination with potassium perfluorobutane sulfonate or KSS (potassium diphenylsulfon-3-sulfonate) for polycarbonate.
Ono, et al., in U.S. Pat. No. 6,727,303 provide a flame retardant aromatic polycarbonate resin composition comprising (1) 100 parts by weight of resin components comprising 50 to 100 wt % of an aromatic polycarbonate resin (component A-1), 0 to 50 wt % of a styrene-based resin (component A-2) and 0 to 50 wt % of an aromatic polyester resin (component A-3); and (2) 0.1 to 10 parts by weight of a silicone compound (component B) which contains an Si—H group and an aromatic group in the molecule based on 100 parts by weight of the total of the resin components, wherein the silicone compound is at least one selected from silicone compounds which have (1) an Si—H group content (Si—H content) of 0.1 to 1.2 mols/100 g and (2) a content of an aromatic group represented by the following general formula (1) (aromatic group content) of 10 to 70 wt %:
wherein X's are each independently an OH group or the residual monovalent organic group having 1 to 20 carbon atoms, and n is 0 or an integer of 1 to 5, with the proviso that when n is 2 or more, X's can differ from one another, and molded articles thereof. A halogen-free polycarbonate resin composition having excellent transparency and dripping preventing properties and molded articles thereof is also provided.
WO 2012/107514, in the name of Meyer et al., provides a flame-retardant thermoplastic molding composition. The composition contains aromatic polycarbonate resin, about 0.01 to 0.15 wt.-% of a salt, wherein the salt is an alkali metal or alkaline earth metal salt of perfluoroalkane sulfonic acid, aromatic sulfimide, aromatic sulfonic acid, and about 0.5 to 10 wt.-% of poly- and/or oligo-aryloxysiloxane as flame-retardant synergist. The composition is characterized in that its flammability rating is better than that of aromatic polycarbonate resin containing only inorganic salt of a derivative from aliphatic or aromatic sulfonic acid, sulphonamide or sulfonimide in accordance with UL-94 V standard, while mechanical and optical properties of the compositions are maintained.
There continues to exist a need in the art for ecologically friendly, transparent polycarbonate compositions which are flame retardant.